Refrigeration



June 9, 1942. c. 'r. ASHBY 2,285,384

' REFRIGERATION Filed Nov. 27, 1939 BY v W %\]VENTOR. Z//W' MAITORNEY.

Patented Jase 9, 1942 j Carl '1. 1mm, Evansville, he, aldgnor to Serve],Inn, New York, N. Y a corporation of Delaware Application November21,1939, Serial No. 308,255

' Claims. (01. lie-119.5)

My invention relates to refrigeration, and

more particularly to a refrigeration system employing evaporation oi!refrigerant fluid in the presence of an inert gas or auxiliary agent.

It is an object of the invention to provide an improvement forcontrolling refrigeration systems of this type, as to effect defrosting,for example, by causing flow of hot vapors in the system into anevaporator or cooling element. I aciliary agent which is inert withrespect to the refrigerant and absorptionliquid. Although I do not wishto be limited thereto, the refrigerant and absorption liquid may beammonia and water, respectively, and the inert gas or auxiliary agentmay be hydrogen.

In Fig. 1 the cooling element or evaporator I0 is disposed in anenclosedspace [5 which may form a food storage compartment of a thermally mpll hthis by providing a flrst path of flow l0 insulated cabinet I6, only aportion of which is for refrigerant fluid from a place of vaporexpulsion to a place of condensation in which refrigerant is liquefiedand from which liquid flows to the cooling element, and a second path offlow through which hot vapor flows from the place of vapor. expulsion tothe .cooling element; --A

liquid trap is provided in the second path of flow, and, when liquid isremoved from me trap, hot

vapor can flow into the cooling element to effect rapid defrosting. Animportant feature of the invention is that the second path of flow isconnected in the refrigeration system in such a manner that when hotvapor is flowingto the cooling element from the place of vaporexpulsion, allof the vapor passes through the second path of flow and noflow of vapor takes place in the first path vof flow. Further, theliquid trap in the second path of flow is arranged to receive liquidfrom a rectifier or other suitable place in the system to insure aneflective liquid sealwhen it is desired to cause all of the refrigerantfluid to flow through the flrstpath of flow to the place of condensationand from the latter to the cooling element for evaporation therein.

The invention, together with the above and other objects and advantagesthereof, willbe more fully understood upon reference to the followingdescription and the accompanying drawing'forming a part of thisspecification, and of which Fig. 1 illustrates more or lessdiagrammatically a refrigeration system embodying the invention; andFig. 21s a fragmentary view 11- lustrating another embodiment of theinvention.

In the drawing I have shown the invention embodied in an absorptionrefrigeration system v of a uniform pressure type containing a pressureequalizing gas or auxiliary agent. A sys-- tern of this'type includes anevaporator or cooling element ll, an absorber H, a generator l2 and acondenser II which are interconnected in a manner well known in the artand which will be briefly described hereinafter. The system contains asolution of refrigerant and absorption liquid, and also a pressureequalizing gas or auxshown. Refrigerant fluid evaporates in coolingelement It and difluses into he inert gas or auxiliary agent to producea re rigerating effect. The resulting gas mixture of refrigerant and 16auxiliary agent flows from cooling element Ill through a conduit ll,inner passage it of a gas heat exchanger l9, and conduit 20 into thelower part of absorber H.

In absorber II refrigerant vapor is absorbed 20 by the absorption liquidwhich enters through a conduit 2!. The auxiliary agent, which is pracetically insoluble and weak in refrigerant, flows through a conduit 22,outer passage 23 of gas heat exchanger 19 and conduit 24 into the lower25 part of cooling element 10.

The circulation of auxiliary agent or inert gas in the gas circuit justdescribed is due to the difference in speciflc weight of column ofauxiliary agent-rich in refrigerant and flowing from the upper part ofcooling element III to absorber II and the column-of auxiliary agentweak in refrigerant vaporand flowing from absorber II to the lower partof cooling element I 0. Since the column of auxiliary agent rich inrefrigerant vapor is heavier than that weak in refrigerant vapor, aforce-is produced or developed for causing circulation of auxiliaryagent through and between cooling element l0 and absorber Il'.

Absorption liquid'enriched in refrigerant flows 40 from the lower partof absorber .ll through a 5 for example, whereby liquid is raised in thegenerator through a tube 8| by vapor liquid lift action and flows backtothe generator through a standpipe I2. Refrigerant vaporis expelled fromsolution in generator l2 due to heating, by burner Ill, and this vapor,together with vapor entering through tube ll, flows through standpipe 22and conduit a into analyzer 2|. In analyzer 28 the expelled vapor flowsthrough a vapor liquid lift tube 34 into an upperchamber "from which theraised liquid drains back through a tube 8'.

conduit to the lower end of trap 50.

From the upper chamber of analyzer 28 the re.- frigerant vapor flowsthrough a conduit 31, an air-cooled rectifier 38, and conduit 39 intothe condenser l4. Refrigerant vapor is liquefied in condenser I4 andreturned to cooling element 10 through conduit 40 to complete therefrigerating cycle.

The weakened absorption fluid from which refrigerant has beenexpelledflows from generator l2 through a conduit 4|, inner passage of liquidheat exchanger 26, and conduit 2! to the upper part of absorber II. Thiscirculation of absorption liquid results from the raising of liquidthrough tube .3] by Vapor liquid lift action.

The heat liberated with absorption of refrig= erant vapor in absorber His transferred to ,'a suitable cooling medium which circulates through acoil 42 arranged in heat exchange relation with the absorber. The coil42 is connected by conduits43 and 44 to a looped coil 45 to form aclosed circuit which is partly filled with a volatile liquid. The liquidevaporates in coil 42 taking up heat from absorber H, and the vaporliquefies in looped coil 49 giving up heat to surrounding air.

., to jacket 53 and transfer of heat from flue 54 to trap 50 ceases whenjacket 53 is depleted of 53 takes up heat from the hot combustion gasesflowing through flue 54, and condensation of the vapors in loop 56 givesup heat to liquid in trap 50 at a sufficient rate to cause vaporizationof liquid in the latter. When valve 58 is closed, liquid is preventedfrom returning through conduit 51 liquid,

During normal operation of the refrigeration system, assuming that trap58 is filled with liquid and control valve 58 is closed, vapor expelledfrom solution in generator [2 flows through a first path of flow whichincludes conduit 33, analyzer'28, conduit 31, rectifier 38, conduit 39and condenser I4. From condenser l4 liquid refrigerant continues to flowin this first path of flow through conduit 48 into cooling element It inwhich the liquid evaporates and diffuses into auxiliary agent to producea refrigerating effect.

. When vapor'is expelled from solution imgenerator l2, some absorptionliquid vapor accompanics the refrigerant vapor. In analyzer 28 the Theoutletend of condenser I4 is connected by a conduit 46, vessel 41 andconduit 48 to a part of the gas circuit, as at the upper end of gas heatexchanger I9, for example, so that any auxiliary agent which may passthrough the condenser can flow into the gas circuit. Refrigerant vapornot liquefied in the condenser flows through conduit 46 to displaceauxiliary agent in vessel 41 and force such agent through conduit 48into the gas circuit. The effect of forcing auxiliary agent into the gascircuit in this manner is to increase the total pressure in the entiresystem to insure condensation of refrigerant vapor in condenser M.

In accordance with my invention, in order to provide a path of flow forhot vapor from generator l2 to cooling element ID, a conduit 49 isconnected at its lower'end to the upper end of conduit 33. The conduit49 is formed with a U- shaped portion to provide a liquid trap 50. Fromthe trap 58 conduit 49 extends upwardly and is connected at its upperend to cooling element 10. The lower end of rectifier 38 is connected bya The rectifier 38 may be provided with a baffie or dam 52 to directliquid flowing downwardly in the rectifier through conduit 5| into thetrap 50.

I Although-liquid in trap 50 may be heated in any suitable manner, Ihave shown a heat transfer system for transferring heat'from generatorl2 to the trap. 'The' heat transfer system includes a jacket 53 disposedabout a flue 54 of generator Ill. The upper part of jacket 53 isconnected by a conduit 55 to the upper part of an annular loop 56. Thesides and lower portion of loop 56 are in good heat exchange relationwith the legs and lower rounded portion of trap 50. The lower part ofloop 56 is connected by a conduit 51 to the lower part of jacket 53. Acontrol valve 58 is provided in conduit 51 to control transfer of heatto trap 50 by the heat transfer system.

The jacket 53, loop 56'and connecting conduits 55 and 51 form a closedfluid circuit which is partly filled with a suitable volatile liquid,such as methyl chloride, for example. Assuming that valve 53 is open,volatile liquid in jacket 53 is heated and vaporized, and the vaporflows through conduit 55 into loop 56 in which it is condensed.

The condensate returns from loop 56 through expelled vapor flows inintimate contact with rich absorption liquid in vapor liquid lift tube34. Since the absorption liquid raised in tube 34 is enriched inrefrigerant as a result of absorption of refrigerant in absorber l I,substantially no refrigerant vapor is absorbed by the enriched liquid inanalyzer 28. However, absorption liquid vapor accompanying therefrigerant vapor is condensed and the raised liquid drains through tube36 into the lower part of analyzer 28.

The refrigerant vapor, which has now been de-' prived to some extent ofaccompanying absorption liquid vapor, flows from analyzer 29 throughconduit 31 into the air-cooled rectifier 38. In rectifier 38 absorptionliquid vapor accompanying the refrigerant vapor is condensed. Theabsorption liquid vapor condenses at a higher temperature than therefrigerant vapor and the temperature of rectifier 38 is such thatrefrigerant vapor substantially deprived of accompanying absorptionliquid vapor continues to flow through conduit 39 into condenser l4 inwhich it is condensed.

The condensate formed in rectifier 38 flows through conduit 5| into trap58, and, when the liquid level in this trap reaches the level Iindicated in the drawing, liquid overflows through conduit 49 andreturns to generator 12.

The temperature at which evaporation of refrigerant takes place incooling element In is dependent upon the partial pressure of refrigerantvapor. During normal operation of the refrigeration system the partialpressure of refrigerant vapor in cooling element I0 is such thatevaporation of liquid takes place at atemperature below the freezingtemperature of water. The cooling element 10 being operated at this lowtemperature, a layer of frost or ice is formed thereon,

due to condensation of water vapor from air flowing in contact with thesurfaces of the cooling element. I

In order to melt the layer of frost or ice formed on the surfaces ofcooling element l0, that is, to effect defrosting of. the latter, liquidis removed from trap 50 to permit hot vapor to flow from the upper partof standpipe 32 through conduit 49 into cooling element ID. When this isdone, the partial pressure of refrigerant vapor in the cooling elementincreases and the temperature of cooling element I0 rises above thefreezing temperature of water. By flowing hot vapor in the systemdirectly into cooling clement III the frost 'aaaaasa through conduit 40'into cooling element no to or ice iccumulated on the latter is meltedvery rapidly.

In the embodiment illustrated; liquid is removed from trap 59 by openingcontrol valve 59. This permits liquid to flow through conduit 51 intojacket 59 whereby heat is transferred from a heated part of the systemto trap 59 in the manner explained above. in trap 59 may be effectedentirely by evaporation of the liquid or by vapor liquid lift action.When the internal diameter of conduit 49 permits the vapor bubblesformed in trap 59 to pass liquid therein, removal of liquid is effectedentirely by evaporation. On the other hand, when the internal diameterof conduit 49 is sufllciently small so that vapor bubbles cannot freelypass liquid in the trap, liquid is removedfrom the trap by vapor liquidlift action. Liquid is removed from the left-hand leg of trap 59 intothe upper end of standpipe 32, and liquid in the right-hand leg of trap59 is raised through conduit '49 into coolingelement l9. Although liquidis removed from trap 59 to permit fiow of hot vapor through conduit 49to cooling element l9, sufficient liquid should remain in conduit 51 toprevent by-passing of hot vapor to rectifier 99 and thence to condenserTo insure blocking oil flow of hot vapor through conduit if when liquidis removed from trap 59, the lower end of conduit is U- shaped to form atrap 69. l he trap 59 is of suchv size that suflicientliquid will alwaysremain therein during the defrosting periods so that all of the-hotvapor flowing through conduit 49 will pass directly into cooling elementl9.

When cooling element i 9 is defrosted, control valve 59 is closedwhereby heat is no longer transferred to trap 59. With cessation of heatsupply to trap 59, condensation of vapor will occur in the upper part ofconduit 49 and such condensate drains back into trap 59 to fill thelatter. If

desired, a plurality of heat transfer fins maybe provided at the upperportion of conduit 49 to aid in filling trap 59 with liquid to terminatea defrosting period. During normal operation of the system, liquiddrains from rectifier 38 through conduit 5| into trap 59, as explainedabove. With this arrangementthe liquid level in trap 59 is maintainedsufiiciently high so that, even with some evaporation of liquid in trap59, the vapor expelled from solution in generator 12 cannot fiow throughconduit 49 during normal operation of the refrigeration system. I

Instead of heating liquid in trap 59-to remove liquid therefrom, asdescribed above in connection with the embodiment in Fig. l, the liquidmay be removed by heating conduit 5|. Such an arrangement is shown -inFig. 2 which illustrates a portion of the system in Fig. 1 with similarparts referred to by the same reference nu-- merals. i

In Fig. 2 liquid in conduit 5| is arranged to be heated by an electricalheating element 59. During normal operation of the refrigeration systemtraps 59 and 69 are filled with liquid and no fiow of hot vapor takesplace through conduit 49. -When it is desired to effect defrosting ofcooling element I9 heating element 59 is connected to a suitable sourceof electrical energy whereby liquid in conduit 5| is heated and vaporbubbles are formed. The internal diameter of conduit 5| in Fig. 2 issufiiciently small so that the vapor bub-' blescannot freely pass liquidwhereby liquid is removed from trap 59 by lifting of liquid in conduit5| by vapor liquid lift action. When the trap 59 is depleted of liquidhot vapor canfiow cause rise in temperature of the latter and rapidmelting of frost formed thereon.

This removal of liquid The size and location of heating elementv 59 ndthe depth of trap. 59 are such that sufficient liquid remains in trap 59whenheating element 59 is energized and cooling element i9 is being' Idefrosted; By properly dimensioning these parts, therefore, all of thehot vapor flows through conduit 49 to cooling element l9 when liquid isremoved from trap 59 and no vapor fiows through conduit 5| due to theliquid remaining in trap 59.

The connection of the vapor by-pflss conduit 49 to the upper end ofconduit 33 is particularly advantageous in that 'all of the. vapor willflow through conduit 49 into cooling element l9 when liquid is removedfrom trap 59. This is so because the liquid in analyzer 29 acts as avalve. In other words, when all ofthe liquid is removed from trap 59there is substantially no resistance to flow of gas through by-passconduit 49, while there is a small liquid head in analyzer 29 throughwhich vapor must pass in order to flow through tube 94 into the upperchamber 25' and thence to condenser l4. When liquid is removed from trap59, therefore, all of the vapor expelled from solution in generator l2fiows into cooling element I9 to effect rapid defrosting. On the otherhand, the provision of returning condensate from recti her 38 to trap 59always insures maintaining a suflicient liquid head in trap 59 which isgreater than that encountered by vapor in analyzer 29 so that flow ofvapor through analyzer 29 is insured during normal operation of therefrigeration system.

While I have shown and described several embodiments of my invention, itwill be apparent to those skilledin the art that modification andchanges may be made without departing from the spirit and scope of theinvention. Thus, liquid may be removed from trap 59 in Fig. 1 by directapplication of heat to the trap without the aid of a heat transfersystem and all of the hot vapor expelled from solution may be caused toflow into the cooling element by providing a liquid head in the systemat a place other than the analyzer. I therefore do not wish to belimited to the embodiments shown in the drawing and described in thespecification and aim in the following claimsto cover all modificationsand changes which fall within the .true spirit and scope of theinvention.

What is claimed is:

l. A refrigeration system including a source of vaporous fluid, acondenser, a cooling element, a conduit including aliquid trap forconducting vapor from said source to said cooling element, said trapbeing arranged to receive liquid, means to remove liquid from said trapto permit flow of vapor through said conduit to said cooling element,and means embodied in said system capable of functioning immediatelywhen sufficient liquid is removed from said trapv to cause all of thevapor from said source to flow through said conduit.

2. A refrigeration system including a source of vaporous fluid, arectifier, a condenser, a cooling element, a conduit including a liquidtrap for conducting vapor from said source to said cooling.

from said trap to permit fiow of vapor through.

said conduit to said cooling element.

3.. A refrigeration system including a source of vaporous fiuid, ananalyzer, a condenser, and a cooling element connected in seriesrelation in the order named, a conduit including a liquid trap forconducting vapor from said source to said cooling element, said trapbeing arranged to receive liquid, and means to remove liquid from saidtrap to permit flow of vapor through said conduit to said coolingelement, said analyzer containing absorption liquid to form a liquidseal whereby all of the vapor from said source flows through saidconduit when liquid is removed from said trap.

4. A method of refrigeration which includes maintaining a supply ofvaporous fluid, flowing vapor from said supply to a place ofcondensation, causing such vapor normally to pass fer of vapor from saidsupply into the presence of evaporating condensed liquid to cause rapidvaporization therein to produce a refrigerating rise in temperature andmelting of any frost which may have formed 'due to said refrigeratingeffect, and utilizing the liquid through which vapor normally passes toblock flow of vapor from said supply to said place of condensation whenvapor is transferred into the presence of evaporating condensed liquid.

5. A method of refrigeration which includes expelling vapor from liquidat a place of vapor expulsion, condensing expelled vapor to liquid at aplace of condensation, evaporating condensed liquid to produce arefrigeration eifect, trapping liquid at a place of accumulation,conducting overflow liquidfrom said place of accumulation to said placeof vapor expulsion, and removing trapped liquid from said place ofaccumulation to cause transfer of expelled vapor from said place ofvapor expulsion into the presence of evaporating condensed liquid tocause rapid rise in temperature and melting of any frost which may haveformed due to said refrigerating effect.

, 6. An absorption refrigeration system having a high temperature placeof heating where vapors are generated and a low temperatureplace whereheat is abstracted by evaporation of liquid to produce a refrigeratingeffect, the place of heat abstraction being subject to formation offrost or ice, structure providing a plurality of paths of flow for fluidfrom the place of heating to the place of heat abstraction, one of thepaths of flow including a portion in which vaporous fluid from the placeof heating is condensed to liquid and from which liquid flows to theplace of heat abstraction and evaporation therein, another of the pathsof flow being adapted to supply vaporous fluid from the place of heatinginto the presence of evaporating liquid at the place of heat abstractionto cause rapid rise in temperature and melting of any frost whichmay'have been formed due to said refrigerating effect, means to controlthe supply of vaporous. fluid to the place of heat abstraction, andmeans in said first path of flow to prevent flow of vaporous fluid tosaid portion in which the fluid is condensed to liquid when vaporousfluid is supplied tothe place of heat abstraction.

7. In the art of refrigeration with an absorption refrigerating systemincluding vaporizing fluid at a place of vapor expulsion, flowing thevaporized fluid to a place of condensation, condensing the vaporizedfluid to liquid in said place of condensation, and flowing liquid fromthe place of condensation to a place of vaporization for formation offrost or ice, the-improvement which consists in also flowing vaporizedfluid from the place of vapor expulsion to the place of vaporization tocause rapid rise in temperature and melting of any frost which may havebeen formed due to said refrigerating effect, and'm'aintaining a liquidseal to block flow of vapor from said place of vaporexpulsion to saidplace of condensation when flowing vaporized fluid to said place ofvaporization.

8. In the art of refrigeration with an absorption refrigerating systemincluding vaporizing fluid at a place of vapor expulsion, flowing thevaporized fluid to a place of condensation, condensing the vaporizedfluid to liquid at the place of condensation and flowing liquid from theplace of condensation to a place of vaporization for vaporizationtherein to produce a refrigerating effect, the place of vaporizationbeing subject to formation of frost or ice, the improvement whichconsists in also flowing vaporized fluid from the place of vaporexpulsion to the place of vaporization to cause rapid rise intemperature and melting of any frost which may have been formed due tosaid refrigerating effect, accumulating liquid at a place ofaccumulation in the path of flow of the vaporized fluid to stop flowthereof to saidplace of vaporization, removing liquid from said place ofaccumulation to permit flow of vaporized fluid to the place ofvaporization,

and stopping flow of vaporized fluid from the place of vapor expulsionto said place of condensation responsive to removal of liquid from saidplace of accumulation. Y

9. In the art of'refrigeration with an absorption refrigerating systemincluding vaporizing fluid at a place of vapor expulsion, flowing thevaporized fluid to a place of condensation, condensing the vaporizedfluid to liquidv at a place of condensation and flowing liquid from theplace of condensation to a place of vaporization for vaporizationtherein to produce a refrigerating effect, the place of vaporizationbeing subject to formation of frost or ice, the improvement whichconsists in also flowing vaporized fluid from the place of vaporexpulsion to the place of vaporization to cause rapid rise intemperature and melting of any frost which may have been formed due tosaid refrigerating effect, flowing liquid in the system to a place ofaccumulation in the path of flow of the vaporized fluid to stop flow ofthe latter to said place of vaporization, conducting overflow liquidfrom said place of accumulation to said placeof vapor expulsion, andremoving liquid from said place of accumulation to permit flow ofvaporized fluid to said place of vaporization.

10. A refrigeration system including a generator, a condenser and acooling element, means including an analyzer for conducting fluid fromsaid generator to said cooling element in a normal path of flowincluding said condenser, a by-pass connection for diverting fluid fromsaid generator to said cooling element without passbefore entering saidcondenser. a connection for conducting fluid from said generator to saidcooling element without passing through said condenser. and means tocontrol said connection. said last-mentioned means being so constructedand arranged that said chamber containing liquid is capable of blockingflow of fluid to said condenser when fluid flows through saidconnection.

12. A refrigeration system as set forth in claim 11 in which said meansto control said connection includes a liquid trap.

13. A refrigeration system as set forth in claim 11 in which aportion'of said connection is utilized to condense fluid flowingtherethrough to 1111 said trap with liquid.

14. A refrigeration system as set forth in claim I ducted to said trap.

a supply of vaporous fluid,

for fluid from said supp y, said condenser providing a for fluid fromsaid supply to a connection around second path of flow nection, and aliquid seal in said first path of flow capable of blocking condenserwhen fluid flows through said connection.

' CARL '1. ASHBY.

system including structure said cooling element, means to control flowof fluid through said 0011- i

